1. Field of the Invention
The present invention relates to a method for manufacturing a substrate for liquid ejection head and a method for manufacturing a liquid ejection head.
2. Description of the Related Art
As a typical liquid ejection head for use in liquid ejection devices, a liquid ejection head having a substrate for liquid ejection head having plurality of energy generation elements that generate thermal energy to be utilized for ejecting liquid and an ejection port member having a liquid ejection port can be mentioned. For the energy generation elements, a heat generation electrical resistance layer that generates heat by energization is used. The heat produced from the heat generation electrical resistance layer causes the generation of bubbles in liquid, and the liquid is ejected from the ejection port by the pressure of the bubbles.
The energy generation elements are covered with an insulating layer containing an insulating material, and a protective layer containing metal materials, such as tantalum, iridium, or ruthenium, is provided on the insulating layer in order to protect the energy generation elements from cavitation impact associated with disappearance of bubbles or chemical action caused by liquid. When the insulating layer of the liquid ejection head has a hole (pinhole), the energy generation elements and the protective layer enter a conductive state, which raises concern that desired heat generation properties are not obtained or an electrochemical reaction occurs between the protective layer and liquid, and therefor the protective layer deteriorates to reduce the durability or is eluted. Therefore, it is required to inspect the insulation between the energy generation elements and the protective layer in a stage of manufacturing a substrate for liquid ejection head.
Japanese Patent Laid-Open No. 2004-50646 discloses a method for inspecting insulation using an inspection terminal connected to a protective layer that is provided in the shape of a belt in such a manner as to protect plurality of energy generation elements in common and an inspection terminal connected to the plurality of energy generation elements in common. According to the method, the plurality of energy generation elements can be collectively inspected for the insulation by an insulating layer.
However, in the structure disclosed in Japanese Patent Laid-Open No. 2004-50646, when a hole is formed in the insulating layer corresponding to one energy generation element due to the influence of cavitation during recording or the like, so that the protective layer and the energy generation elements enter a conductive state, a current flows also to the protective layer covering the other energy generation elements. Therefore, the entire protective layer causes an electrochemical reaction with liquid, which causes deterioration in the protective layer on the plurality of energy generation elements in common.
In order to overcome the problem, it is considered that the protective layer is electrically disconnected from each other and independently provided for each energy generation element. However, in such a case, the inspection for confirming the insulation between the protective portions and the energy generation elements need to be performed for each energy generation element, which requires a huge number of inspection terminals and huge time for the inspection. Thus, the efficiency is not good.